The emergence of bacterial pathogens that are resistant to major classes of antibiotics poses a serious public health threat and has created demand for novel antibacterial agents. These new antibacterial agents should be directed to act on novel drug targets. Bacterial genomics will provide many new potential drug targets. The limitation for antibacterial drug discovery, however, is that for many of these targets there will be little or no knowledge of their biochemical function. This grant proposes to develop a platform to identify novel antibacterial agents that act on targets of unknown function. Preliminary results have shown that enzyme-specific peptides isolated by phage display can be used as probes to detect enzyme inhibitors. The research in this grant would involve cloning, overproducing, and purifying three essential gene products from E. coli. Peptides would then be identified, using phage display, that specifically bound to each of these essential gene products. Inhibition of an essential function by the peptides would be validated by expressing the peptides in E. coli and monitoring cell growth. Validated peptides would be used to format an assay and perform a high throughput screen. Hits from the HTS would be tested for antibacterial activity. PROPOSED COMMERCIAL APPLICATION Peptide ligands will be used as molecular probes in high throughput screening assays to identify small chemical compounds (leads) in antibacterial drug discovery. This technology will provide a method to identify inhibitors of targets whose biochemical activity is unknown. We anticipate that some of the compound leads obtained from our screening strategy will move on to drug development.